Automatic galvanizing machines

ABSTRACT

Automatic production line galvanizing machines perform multiple dipping of baskets, racks, or hook work into molten zinc, with successive withdrawals and immersions of work in the molten zinc bath, provided by simple automatic mechanisms. An overhead monorail conveyor carries worksupporting retractable pendant hooks from a loading station to the galvanizing station, where automatic raising and lowering sub-tracks raise the pendants upwardly to withdraw the work from the zinc bath, and extend the retractable pendant downwardly to immerse the work in the zinc bath in repeated withdrawal and immersion steps. Each worksupporting pendant is then carried by the endless monorail conveyor to subsequent operations either performed on the supporting hooks or by disengaging loads from the conveyor. The pendants return to the loading station to begin the next galvanizing cycle, automatically picking up or hooking the next loads. Economical assemblies of standard conveyor components are combined with unique retractable pendants operated by elevatable sub-tracks to provide highly effective and unusually economical automatic galvanizing apparatus.

United States Patent [19] Hammer [451 Jan. 21, 1975 AUTOMATIC GALVANIZING MACHINES 22 Filed: Apr. 8, 1974 21 Appl. No.: 458,480

Related US. Application Data [63] Continuation-impart of Ser. No. 299,757, Nov. 24,

1972, abandoned.

[52] US. Cl 118/425, 104/127, 104/128, 198/177 R, 214/89, 294/82 R [51] Int. Cl. 1305c 3/09 [58] Field of Search 118/423, 425, 500, 501, 118/503; 294/82 R; 214/86 R, 89; 198/177 R [56] References Cited UNITED STATES PATENTS 527,628 10/1894 Thomas 118/423 X 839,719 12/1906 Broderick 118/423 UX 856,996 6/1907 Custer et al. 118/423 X 1,498,691 6/1924 Kearns 294/82 R 2,750,923 6/1956 Daniel 118/425 X 2,764,124 9/1956 Reed et a1 118/425 X 2,824,029 2/1958 Zinty 118/425 UX 2,997,018 8/1961 McGraw, Jr... 118/423 X 3,262,420 7/1966 Bossi et al 118/423 X 3,507,251 4/1970 Thayer et al 118/425 3,828,419 8/1974 Wanner 118/400 Primary Examiner-Morris Kaplan Attorney, Agent, or FirmMattem, Ware & Davis [5 7] ABSTRACT Automatic production line galvanizing machines perform multiple dipping of baskets, racks. or hook work into molten zinc, with successive withdrawals and immersions of work in the molten zinc bath, provided by simple automatic mechanisms. An overhead monorail conveyor carries worksupporting retractable pendant hooks from a loading station to the galvanizing station, where automatic raising and lowering sub-tracks raise the pendants upwardly to withdraw the work from the zinc bath, and extend the retractable pendant downwardly to immerse the work in the zinc bath in repeated withdrawal and immersion steps. Each worksupporting pendant is then carried by the endless monorail conveyor to subsequent operations either performed on the supporting hooks or by disengaging loads from the conveyor. The pendants return to the loading station to begin the next galvanizing cycle, automatically picking up or hooking the next loads. Economical assemblies of standard conveyor components are combined with unique retractable pendants operated by elevatable sub-tracks to provide highly effective and unusually economical automatic galvanizing apparatus.

10 Claims, 8 Drawing Figures PATENTED JANZ 1 I975 SHEET 3 BF 3 AUTOMATIC GALVANIZING MACHINES RELATED APPLICATIONS This application is a continuation-in-part application of my copending U.S. Pat. application bearing Ser. No. 299,757, filed Nov. 24, 1972, now abandoned.

BACKGROUND OF THE INVENTION This invention relates to machines for performing processes requiring dipping movements, such as assembly, plating, painting and automatic hot dip galvanizing machines, and particularly to comparatively small and economical automatic production line machines requiring only a modest capital outlay, and capable of high volume galvanizing production of basket-carried workpieces, hook work or galvanizing racks of workpieces.

THE PRIOR ART My U.S. Pat. Nos. 3,493,093 and 3,500,979 show two forms of automatic production line galvanizing machines. U.S. Pat. No. 3,493,093 shows a relatively large galvanizing conveyor system, employing cam actuated work-carrying hooks mounted on articulating pivoted hook supports, which are caused to move angularly by the operation of cam and cam follower devices incorporated in the overlying monorail. These machines are highly effective for large industrial galvanizing operations, but they require considerable capital investment to build, install and service.

My U.S. Pat. No. 3,500,979 describes a smaller ro tary galvanizing machine providing unique forward and vertical maneuverability, producing a highly effective manual galvanizing operation.

Many other patents have attempted to solve the problem of raising and lowering workpieces or racks or baskets of parts while moving them along a galvanizing or processing conveyor line. For example, U.S. Pat. Nos. 839,719; 856,996, 1,318,054; 1,613,878; 1,753,350; 1,971,220; 2,175,788; 2,750,923; 2,764,124; 2,997,018 and 3,507,251 all show various complex contrivances for raising and lowering workpieces during processing operations. Many of these devices incorporate extra endless chains and involved mechanisms for achieving this purpose.

Galvanizers with small or medium sized production runs do not require the high volume production capabilities of the large galvanizing machines that are shown in my U.S. Pat. No. 3,493,093, but they often require automatic galvanizing equipment for the hot dip coating of many hundreds or thousands of workpieces. Manual maneuvering of this many workpieces introduces prohibitively high labor costs, and the introduction of high volume automatic machinery requires prohibitively high capital investment.

For this reason there has been a long felt need for automatic high quality galvanizing machines providing automatic galvanizing cycles for small and medium sized production runs. In the past no economically practical automatic galvanizing machine has filled this need.

SUMMARY OF THE INVENTION The present invention fills this need with great effectiveness by providing an automatic cycling endless monorail overhead conveyor of any desired length, fabricated of conventional, commercially available conveyor components. Carried on this conveyor are a series of spaced roller trolleys supporting retractable pendant hooks positioned for carrying racks, baskets or individual workpieces around the galvanizing conveyor. A portion of the monorail is positioned at a low, galvanizing dip level, directly above a galvanizing kettle containing molten zinc, and incorporating conventional draining, refilling, and heating units for maintaining the molten zinc at the desired galvanizing temperature. The retractable pendants are provided with lateral protruding wings or discs positioned to pass above horizontal sub-tracks underlying the lower galvanizing dip portion of the monorail conveyor. The sub-tracks are suspended from overhead support mechanisms, which are capable of raising and lowering the sub-tracks and the retractable pendants, following a predetermined cycle of vertical movement.

When raised, the sub-tracks engage the lateral protruding wings or discs of the retractable pendants, causing them to retract and withdraw the workpieces from the galvanizing zinc bath between successive dips, for intermediate draining of excess molten zinc. Downward movement of the sub-tracks lowers the lateral protruding wings or discs, permitting the retractable pendants to extend, lowering the hook-supported workpieces to full galvanizing depth in the zinc bath. After the predetermined dipping and draining steps have been performed, the monorail carries the work piece supporting trolley pendants upward away from the galvanizing kettle to subsequent operations either performed on the supporting hooks or after disengaging loads from the conveyor at an unloading station, and the pendants are carried by the conveyor to a reloading station where the pendant hooks are either manually or automatically loaded with workpieces for the next galvanizing cycle.

Accordingly, a principal object of the invention is to provide automatic galvanizing machines capable of high volume galvanizing of workpieces, incorporating inexpensive, commercially available component parts.

Another object of the invention is to provide such galvanizing apparatus capable of successive predetermined dipping and draining movement of the workpieces into and out of the galvanizing bath during the galvanizing operation.

A further object of the invention is to provide successive dipping and draining workpiece movement by utilizing commercially available overhead conveyor devices cooperating with retractable pendant workpiece supports, raised and lowered to provide the predetermined successive dipping and draining workpiece movement by operation of inexpensive pendant retractable mechanisms.

Another object of the invention is to provide such galvanizing apparatus capable of high quality high volume automatic galvanizing operation combined with unexpectedly economical initial cost, roughly one-third of conventional acquisition cost for similar machines sold in the past.

A further object of the invention is to provide such automatic galvanizing apparatus capable of high volume automatic galvanizing operation without requiring constant operator attention, resulting in a labor cost reduction of percent or more.

Other and more specific objects will be apparent from the features, elements, combinations and operating procedures disclosed in the following detailed description and shown in the drawings.

FIG. 1 is a side elevation view ofa portion of an automatic endless conveyor galvanizing machine incorporating the present invention, showing the galvanizing kettle and the workpiece'supporting conveyor and associated mechanisms.

FIG. 2 is a transverse cross-sectional elevation view taken along the plane 2-2 of FIG. 1, showing a workpiece-supporting telescoping pendant in its extended, galvanizing dip position, and FIG. 2A is a fragmentary side elevation view, partially in section, showing an alternative subassembly.

FIG. 3 is a corresponding transverse cross-sectional elevation view showing the telescoping workpiecesupporting pendant in its upwardly retracted draining position, supporting the workpiece above the level of the surface of the galvanizing bath.

FIG. 4 is an enlarged elevation view of one of the telescoping pendants of the invention in its extended position.

FIG. 5 is a corresponding enlarged elevation view of the same telescoping pendant in its retracted position.

FIG. 6 is a fragmentary side elevation view showing an alternative form of retractable pendant in successive positions, and

FIG. 7 is a fragmentary end elevation view showing the pendant of FIG. 6.

ENDLESS OVERHEAD MONORAIL CONVEYORS The overhead monorail conveyors in the present invention are formed in endless conveyor configurations of conventional shape, designed for convenient installation in the users plant. These endless conveyors are provided with workpiece carrying roller trolleys spaced at equal intervals along the conveyor rail, and maintained in this spaced relationship by engagement with.

drive lugs positioned by swaging or set screws or U-bolt clamps on a connecting drive cable, preferably a twisted stainless steel cable for maximum useful life. Changes of direction or corners of the overhead monorail are provided with 90 or 180 corner sprocket assemblies incorporating notched sprocket wheels re ceiving and engaging the spaced trolleys. One or more of these sprocket wheels may be provided with a variable speed or constant speed drive.

Additional spacing lugs may be secured to the drive cable at intermediate points between trolleys when a wider trolley spacing is desired.

A suitable inexpensive commercially available overhead monorail trolley cable conveyor suitable for use in devices of the present invention is the line of American Cable-Way conveyors sold by the American Monorail Division of Eaton Yale & Towne Inc. of l 1 l 1 East 200th Street, Cleveland, Ohio 441 17.

In the drawings, the endless monorail conveyor generally indicated at 10 comprises an I beam cross section rail 11 having a lower flange l2. Rollers 13, mounted on trolleys 14, are spaced apart at equal intervals along a drive chain or cable 16, to which the trolleys are anchored by drive lugs 17 as shown in FIG. 1. Centrally positioned on cable 16 between trolleys 14 are similar spacer lugs 18, which are similarly anchored to the cable in spaced relationship between the trolleys 14. Drive lugs 17 and spacer lugs 18 are spaced apart along the cable by predetermined distances corresponding to the peripheral distance between drive notches of corner sprocket wheels, mounted at the corners of the conveyor 10, at which the cable 16 changes its horizontal direction. Corner sprocket wheels are located at points not shown in FIG. 1 beyond the length of conveyor 10 there illustrated. For example, viewed in plan from above, conveyor 10 may be arranged in a rectangular configuration with a sprocket wheel in each corner, one of more of which may be a driving sprocket wheel powered by a suitable drive motor. Changes of direction of cable 16 in a vertical plane are governed by the shape of the rail 11 as illustrated in FIG. 1, where angular vertical offsets bending the path of the cable 16 and its associated trolleys 14 through an arc in the vertical plane are formed at each end of the segment of rail 11 there shown. Taking the rail 11 from the left side of FIG. 1 and proceeding toward the right side of the same Figure the rail 11 enters FIG. 1 at a high level, supporting the leftmost trolley 14 with its depending telescoping pendant 19 fully extended, supporting its basket 21 of workpieces to be treated at a level above the rim of the galvanizing kettle 22, at a suitable height for moving delivery of the basket 19 around conveyor 10 from its loading station through the galvanizing operation illustrated in FIG. 1. Immediately after entering FIG. 1, rail 11 enters a downwardly curving arcuate portion 11A, blending smoothly with a straight descending entrance ramp 1 1B. This portion of rail 11 merges smoothly with an upwardly curving arcuate portion llC, which blends smoothly with a straight horizontal low level portion 1 1D extending along a substantial part of the length of kettle 22.

This horizontal lower level portion 11D of the monorail conveyor 11 is positioned at immersion height above the kettle 22, producing full galvanizing dip immersion of objects, trays or baskets carried by fully extended telescoping pendants 19 supported by trolleys 14, as these trolleys move forward along this low level horizontal conveyor rail portion 11D.

As shown in FIG. 1, the low level portion 11D blends smoothly with an upwardly curving arcuate portion 11E which merges with an ascending exit ramp portion 11F positioned at the opposite end of kettle 22, which blends with a downwardly curving arcuate portion merging with a conventional high level horizontal conveyor rail portion 11H comprising the remaining portion of the endless conveyor 10, including idler sprocket wheels, drive sprocket wheels, and unloading and loading stations between the conveyor portion 11G at the right hand side of FIG. 1 and the downwardly curving entrance portion 11A of the conveyor rail shown at the left-hand side of FIG. 1, thus forming a complete circuit endless conveyor system.

RAISED AND LOWERED SUB-TRACKS Positioned on both sides of the forward plane of movement of pendants 19 traveling along the low level kettle portion 11D of the monorail conveyor 10 are a pair of liftable sub-tracks 23 preferably comprising rolled anglesection steel beams 24 depending from supporting vertical columns 26, whose upper ends are anchored in lift blocks 27 adapted to be raised and low ered by a lifting mechanism. This may take the form of the piston-cylinder lifting units 45 shown in FIG. 2A, or other lifting devices such as the supporting chain 28, sprocket 29, and suitable torquing means such as lever 31, shown in FIG. 2. Angular movement of lever 31 from its rest position shown in FIG. 2 to its actuated position 31A shown in FIG. 3, rotates sprocket wheel 29 through an angular are causing the depending portion of chain 28 to be drawn upward around the sprocket wheel 29, raising lift block 27 and depending columns 26 from their rest positions shown in FIG. 2 to their actuated, raised positions shown in FIG. 3. Axial rising movement of columns 26 is guided by means associated with and preferably anchored to the low level immersion portion 11D of the monorail conveyor 10, such as sleeve bearings 31. These may be bushings mounted in bearing blocks 32, which are secured by welding for example to the top flange of rail 11 above the ends of subtracks 23 near the ends of horizontal immersion rail portion 11D.

LIFTING OF WORKPIECES FROM KETTLE The lifting movement of the sub-tracks 23 is clearly shown in FIGS. 1, 2 and 3. In the lowermost position of subtrack 23 shown in solid lines in FIG. 1 and also shown in FIG. 2, the angle beams 24 flanking the extended telescoping pendants '19 are lowered to clear the protruding wing projections 33 protruding laterally from outer sleeve portions 34 of each telescoping pendant 19. Projections 33 hereinafter called wings or wing means, may take the form of short bars, as shown in the drawings, or discs protruding concentrically from the upper end of each sleeve portion 34. A vertically protruding post portion 36 of each pendant 19 is installed inside each sleeve portion 34, free for vertical sliding telescoping movement from the extended position shown in FIGS. 2 and 4 and in solid lines in FIG. 1 to retracted position shown in FIGS. 3 and 5 and in dash lines in FIG. 1. Thus, when sub-tracks 23 are lowered, the pendants passing therebetween are fully extended, as shown in FIG. 2.

In the raised position of sub-tracks 23 shown in FIG. 3 and in dash lines in FIG. 1, the angle beams 24 have moved upward into lifting contact with wings 33 extending laterally from the upper end of the sleeve portion 34 of the telescoping pendants 19, raising sleeve portions 34 into the telescoped positions, shown in FIGS. 3 and 5, and correspondingly raising the galvanizing workpieces which are suspended from hooks 37 at the lower end of each telescoped pendant 19 by such means as the depending baskets 21.

In hot dip galvanizing operations, the preferred raised position of the workpieces shown in FIG. 3 withdraws the workpieces almost entirely from the hot zinc galvanizing bath, but leaves their lower ends slightly immersed. This promotes the draining of excess molten zinc therefrom during the raised portion of the galvanizing treatment, in order to prepare the previously galvanized surface for the next succeeding immersion to produce the desired uniform galvanized coating on the workpieces. This slight immersion of the workpieces and the supporting baskets 21 just below the molten zinc surface 38 is shown in FIG. 3 and in dash lines in FIG. 1.

One preferred form of telescoping pendants 19 of the present invention useful with galvanizing basket 21 is shown in detail in the enlarged views of FIGS. 4 and 5, where the outer sleeve portion 34 of the pendant 19 is formed of a standard length of pipe threaded at both ends, with a simple threaded cap 39 mounted at the lower end. Threaded terminal cap 39 supports the workpiece hooks 37, while an upper end cap 41 is provided with laterally extending wings projections 33,

formed as threaded posts anchored in threaded apertures formed in the sides of each cap 41. The upper end caps 41 are also provided with an aperture formed in their upper end faces accommodating the sliding axial telescoping movement of the post portion 36 into and out of the interior of sleeve portion 34, between the positions shown in FIGS. 4 and 5. As shown in FIG. 5, the maximum telescoping withdrawal of post portion 36 within sleeve portion 34 brings the lower end of the post portion 36 into abutting engagement with the inside of the lower end cap 39. The extent of telescoping extension of post portion 36 as it moves out of telescoped overlapping engagement through the aperture in cap 41 is governed by the distance from the lower end of the post portion 36 to a captive retainer, which may take the form of a removable screw 42 shown in FIG. 4, threaded into one of a plurality of threaded apertures 43 formed in the post portion 36, and protruding into captive interfering engagement with the inside of the upper end cap 41 by extending sufficiently far from the surface of the post portion 36 to interfere with and abutt against the interior of cap 41 beyond its telescoping aperture. Insertion and adjustment of captive retainer screw 42 in the selected one of the plurality of apertures 43 is performed through an access aperture 44 in sleeve portion 34 of the telescoping pendant 19. A supporting ring 46 secured to the upper end of the post portion 36 of the telescope pendant 19 is engaged with the lower end of each trolley 14, positioning each pendant 19 with its wings 33 protruding laterally to pass above the sub-tracks 23 in their lowered positions as shown in FIG. 2, 39 and and to engage with and be lifted by the raised sub-tracks 23 in their raised position shown in FIG. 3. Pendants 19 are preferably oriented with hooks 37 opening forward to receive new baskets 21 during loading. To assure this orientation and to maintain wings 33 protruding laterally for engagement with sub-tracks 23, post portion 36 may be square in cross section or otherwise non-symmetrical, and telescoping aperture 40 in cap 41 may have a mating shape, to prevent rotation of portion 36 relative to portion 34. For simplicity lower cap 39 hooks 37 are shown rotated in FIGS. 4 and 5 from their true positions shown in FIGS. 1, 2 and 3.

Lever 31 and chain-sprocket assemblies 28-29 may be replaced by conventional air cylinders or hydraulic cylinders for raising the lift blocks 27, and suitable timing or programming systems may be employed to cause the workpieces carried by conveyor 10 to be raised and lowered as many times as may be desired for optimum galvanizing treatment in kettle 22.

By way of an example, the workpiece path shown by dashed arrows in FIG. 1 illustrates a three dip galvanizing process in which entering baskets 21 are moved downward depending beneath conveyor segments 11 A, 11 B, 11 C into immersion beneath the surfaces 38 of the hot molten zinc in kettle 22, and then raised to dash line positions and lowered to solid line positions successively when sub-tracks 23 are raised and lowered as the pendants 19 are drawn by cables 16 along the horizontal galvanizing portion 11D of the monorail conveyor 10, moving from left to right across the central portion of FIG. 1 between the columns 26, and then moving upwardly and away from kettle 22 beneath conveyor sections 11E, 11F and 116, to be carried toward an unloading station and thence to a loading station and back to conveyor sections 1 1A, 118 and 11C for the next immersion in the kettle.

Any desired program of actuating movement of lever 31 or other means for raising and lowering lift blocks 27 may be employed to produce any desired number and length of immersions and withdrawals of workpieces from the surface 38 of hot molten zinc in kettle 22, to produce any number of dip and drain steps desired for optimum galvanizing treatment of workpieces. The use of standard, conventional overhead monorail conveyor tracks, trolleys and cables with the telescoping pendants and sub-tracks assemblies of the present invention provides desirable flexibility in the height, length and capacity of the galvanizing systems of this invention, while minimizing their capital asset acquisition cost in a highly desirable manner, making these systems available to galvanizing shops of all sizes. Different variable speed drives and manual override control governing the upward movement of subtracks 23 enhances the flexibility of the systems, adapting them for galvanizing treatment of workpieces having wide varieties of shapes, sizes and weights.

KNEE-ACTION PENDANTS An alternative form of retracting pendant is typified by the pendant 51 shown in FIGS. 6 and 7. This pendant incorporates a pivoted double-link lever having a cable-driven roller trolley 52 movably supported by the lower flange of an overhead conveyor monorail 53.

The retractable portion of pendant 51 comprises a knee-action two-part linkage incorporating an upper link 54 whose upper end is suspended by a pivot pin 56 from trolley 52, and a lower link 57 whose upper end is pivotally secured near the lower end of upper link 54 by a pivot pin 58.

A movable hook 59 secured to the lower end of lower link 57 carries the workpieces to be galvanized, either directly or by such carrying means as a rack or the basket 61 shown in FIGS. 6 and 7.

A stop pin 62 extending laterally from the lower end of upper link 54 limits the angular pivoting movement of link 57 relative to link 54, as shown in dash lines at the left hand side of FIG. 6. As sub-tracks 23 are lifted from the lower position to the upper retracted position shown in dotdash lines at the right-hand side of FIG. 6, they engage wings 63 extending laterally from lower link 57. This causes the knee-action linkage 54-57 to pivot elbow-fashion about pivot pin 58 to the retracted, raised configuration shown in dot-dash lines at the right hand side of FIG. 6, raising basket 61 to its upper, draining position.

Lowering of sub-tracks 23 permits pivoting, straightening extension of linkage 54-57 until stop pin 62 engages lower link 57, assuring that this linkage will toggle or flex in the desired direction during the next retraction operation, permitting the desired forward conveyor movement as trolley 52 continues along monorail track 53.

Thus the desired successive raising and lowering operation shown schematically in FIG. 1 is achieved by the conveyor systems of this invention utilizing either form of retractable pendant, the telescoping pendant of FIGS. 25, or the knee-action pendant of FIGS. 6 and 7. In all cases, the raising of subtracks 23 retracts the pendant 36 or 51, raising the workpieces as required.

Since the foregoing description and drawings are merely illustrative, the scope of the invention has been broadly stated herein and it should be liberally interpreted to secure the benefit of all equivalents to which the invention is fairly entitled.

What is claimed is:

1. workpiece immersion treatment apparatus for hot dip galvanizing or like operations incorporating:

A. an elongated kettle containing an immersion bath,

B. an overhead rail conveyor having a low portion extending over the kettle connecting higher entrance ramp and exit ramp portions,

C. trolleys mounted for rolling movement spaced apart along the rail,

D. a vertically retractable pendant depending from each of the trolleys,

E. workpiece support means mounted at the lower end of each pendant at a level selected for workpiece immersion in the bath,

F. drive means propelling the spaced trolleys and pendants along a treatment path defined by the rail, and

G. pendant elevating means positioned to retract and extend said pendants beneath the low rail portion, producing successive immersion and withdrawal of bath-treated workpieces travelling the length of the kettle.

2. The treatment apparatus defined in claim 1 wherein pendant elevating means comprises sub-track means positioned beside the pendants travelling the length of the kettle, and positioned to engage a lower portion of said travelling pendants, and retraction means for raising and lowering said sub-track means upon command, producing retraction and extension of said travelling pendants.

3. The treatment apparatus defined in claim 1 wherein the retractable pendants each comprise a pivoted knee-action linkage having an upper link pivotally connected to one of the trolleys, and a lower link carrying the workpiece support means and pivotally connected to the upper link, whereby said upper and lower links are relatively pivotable from a vertically extended condition to a pivoted, vertically retracted condition.

4. workpiece immersion treatment apparatus for hot dip galvanizing or like operations incorporating:

A. an elongated kettle containing an immersion bath,

B. an overhead rail conveyor having a low portion extending over the kettle connecting higher entrance ramp and exit ramp portions,

C. trolleys mounted for rolling movement spaced apart along the rail,

D. a vertically retractable pendant depending from each of the trolleys,

E. workpiece support means mounted at the lower end of each pendant at a level selected for workpiece immersion in the bath,

F. drive means propelling the spaced trolleys and pendants along a treatment path defined by the rail,

G. said pendant comprising a relatively elongated rod depending from said trolley, a sleeve element carrying said workpiece support and telescopically associated with the lower section of said rod, and means laterally extending from said sleeve,

H. horizontally extending rail means aligned with and normally disposed intermediate said laterally extending means and said kettle, and

I. means vertically reciprocating said rail means whereby to operatively associate said laterally extending means with the rail means to effect successive immersions of each workpiece traveling the length of the kettle.

5. The apparatus defined in claim 4, wherein the means to vertically reciprocate comprise at least one column having a lower end supporting said rail means and having an upper end connected to column raising and lowering means.

6. The apparatus defined in claim wherein the column raising and lowering means comprises a vertically retractable pressure cylinder and piston assembly.

7. The apparatus defined in claim 5 wherein the column raising and lowering means comprises at least one rotatable sprocket engaging a chain depending therefrom and having a distal end dependingly supporting tending means. 

1. Workpiece immersion treatment apparatus for hot dip galvanizing or like operations incorporating: A. an elongated kettle containing an immersion bath, B. an overhead rail conveyor having a low portion extending over the kettle connecting higher entrance ramp and exit ramp portions, C. trolleys mounted for rolling movement spaced apart along the rail, D. a vertically retractable pendant depending from each of the trolleys, E. workpiece support means mounted at the lower end of each pendant at a level selected for workpiece immersion in the bath, F. drive means propelling the spaced trolleys and pendants along a treatment path defined by the rail, and G. pendant elevating means positioned to retract and extend said pendants beneath the low rail portion, producing successive immersion and withdrawal of bath-treated workpieces travelling the length of the kettle.
 2. The treatment apparatus defined in claim 1 wherein pendant elevating means comprises sub-track means positioned beside the pendants travelling the length of the kettle, and positioned to engage a lower portion of said travelling pendants, and retraction means for raising and lowering said sub-track means upon command, producing retraction and extension of said travelling pendants.
 3. The treatment apparatus defined in claim 1 wherein the retractable pendants each comprise a pivoted knee-action linkage having an upper link pivotally connected to one of the trolleys, and a lower link carrying the workpiece support means and pivotally connected to the upper link, whereby said upper and lower links are relatively pivotable from a vertically extended condition to a pivoted, vertically retracted condition.
 4. Workpiece immersion treatment apparatus for hot dip galvanizing or like operations incorporating: A. an elongated kettle containing an immersion bath, B. an overhead rail conveyor having a low portion extending over the kettle connecting higher entrance ramp and exit ramp portions, C. trolleys mounted for rolling movement spaced apart along the rail, D. a vertically retractable pendant depEnding from each of the trolleys, E. workpiece support means mounted at the lower end of each pendant at a level selected for workpiece immersion in the bath, F. drive means propelling the spaced trolleys and pendants along a treatment path defined by the rail, G. said pendant comprising a relatively elongated rod depending from said trolley, a sleeve element carrying said workpiece support and telescopically associated with the lower section of said rod, and means laterally extending from said sleeve, H. horizontally extending rail means aligned with and normally disposed intermediate said laterally extending means and said kettle, and I. means vertically reciprocating said rail means whereby to operatively associate said laterally extending means with the rail means to effect successive immersions of each workpiece traveling the length of the kettle.
 5. The apparatus defined in claim 4, wherein the means to vertically reciprocate comprise at least one column having a lower end supporting said rail means and having an upper end connected to column raising and lowering means.
 6. The apparatus defined in claim 5 wherein the column raising and lowering means comprises a vertically retractable pressure cylinder and piston assembly.
 7. The apparatus defined in claim 5 wherein the column raising and lowering means comprises at least one rotatable sprocket engaging a chain depending therefrom and having a distal end dependingly supporting said column.
 8. The apparatus defined in claim 4 wherein said pendant includes means limiting the extremes of sleeve movement on said rod.
 9. The apparatus defined in claim 4 wherein said horizontally extending rail means and trolley spacings are of extents whereby a plurality of said sleeve elements are simultaneously engaged for reciprocatory movement.
 10. The apparatus defined in claim 4 wherein said horizontally extending rail means comprise a pair of rail elements flanking said path and each of said elements associated with at least one of said laterally extending means. 